Posters on this forum can also be very "lay-friendly", so no need to worry about answers that may appear too technical.
The simple and un-technical answer: it would be cost-prohibitive to transform your TLM103 into a U87.
The reason: the two microphones are powered by two entirely different, incompatible methods: one has an assembly of individual, discrete, electronic components, the other is powered by tiny microchips. To design and install a new circuit board completely laid out with discrete components where none existed, and in the relatively small space available inside the TLM 103's body, would not make sense, financially.
The much cheaper solution to your whistling and static noise problem: a professional capsule cleaning, to restore the mic to factory-fresh performance.
P.S.: A simple test to evaluate the source of the noise: if it can be triggered or changed in intensity by speaking closely into the mic, it is a case of capsule contamination remedied by cleaning. If, even before you speak into the mic, the mic makes these noises, then the cause may be what Uwe suggested below.